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Download Lect 7 hormones 3
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Control of extracellular Calcium • Today • – Finish hormonal control of calcium – Reproductive hormones (text 664-665; 673678;686) – Study tips Vitamin D Skin Diet 7-dehydrocholesterol sunlight Hormonal Control 1. Parathyroid hormone (PTH) 2. Calcitriol (1,25 dihydroxyvitamin D) 3. Calcitonin 1,25-OH Vitamin D acts as a co-factor to ↑ transcription of a Ca++ channel in the intestinal epithelium Vitamin D3 Plasma Vitamin D Vitamin D Liver 25-OH Vitamin D Kidney 25-OH Vitamin D Parathyroid Hormone 1,25-OH2 Vitamin D GI tract 1,25-OH2 Vitamin D Ca++ transcription Ca++ Na+ Intestinal epithelial cell Plasma 1,25-OH2 Vitamin D 1 Calcitonin • Produced in parafollicle cells of the thyroid gland (C-cells) • High Blood Ca++ stimulates release of calcitonin (also by a calcium-sensing receptor) • Act to decrease blood Ca++ by High Ca++ Calcitonin Mobilize Ca From Bone Low blood Ca++ ↑ Parathyroid hormone ↑1,25 OH2 Vit D from kidney Reabsorb Ca In the kidney – ↓ Ca++ release from bone – ↓ Ca++ reabsorption in kidney Increase absorption of Ca++ from intestine restore blood Ca++ Reproductive Hormones Tissues: 1. Produce gametes: sperm or ova Male - Testes Female - Ovaries 2.Secrete hormones: testosterone, or estrogen, progesterone Testosterone Estradiol 2 Cell Types • Males – nearly constant levels of hormones – Continuous production of sperm Male Female Germ Cell Sperm Ova Support Sertoli Granulosa Receive FSH, stimulate germ cells, secrete inhibin Interstitial Leydig Theca secrete androgens Cell Type Function • Females – Monthly cycle of hormone levels – All germ cells present at birth (2-4 million), no new ones are produced – ~400 will be ovulated Hormonal Control of Spermatogenesis Hypothalamic neurons • Picture of sertoli and leydig cells GnRh Seminiferous tubule FSH only Leydig Cells Anterior Pituitary FSH sperm Sertoli Cells Sertoli Cell spermatogenesis LH only LH Leydig cell testosterone inhibin testosterone 3 Ovary and stages in oocyte maturation • ovarian follicle Granulosa cells Oocyte antrum LH FSH Blood concentration • GnRH – cyclical release ~28 days from hypothalamus • FSH/LH from pituitary • Estrogen & progesterone from ovary Blood concentration Thecal cells Estrogen Progesterone 1 Follicular Phase 15 days Luteal Phase 28 4 Hormonal Control during early & middle follicle phase Corpus luteum Hypothalamic neurons GnRh Mainly FSH Anterior Pituitary LH FSH Theca cell Granulosa Cell oogenesis inhibin estrogen androgens Estrogen Hormonal Control of during late follicle phase Hypothalamic neurons • Low concentrations of estrogen → negative feedback to Ant. Pit & Hypoth → reduced GnRH, LH, FSH • High concentrations of estrogen for 1-2 days → positive feedback to Ant. Pit → more LH, FSH GnRh Anterior Pituitary LH surge ovary Large amount estrogen ovary ovulation corpus luteum Estrogen & Large amount of progesterone 5 5. ovulation • If pregnancy does not occur, Corpus luteum degenerates in about 14 days → progesterone levels start ↓ LH FSH 6. Corpus luteum forms secretes progesterone & estrogen 3.Dominant follicle secrete estrogen 8. Corpus luteum degenerates progesterone & estrogen secretion goes down 2. FSH/LH stim estrogen Estrogen Progesterone 1 Follicular Phase Changes in the uterus: 7. Progesterone from Corp Lut inhibit GnRH, LH, FSH 1.GnRh stim FSH & LH Blood concentration Luteal Phase • Large amount of progesterone from corpus luteum → negative feedback to Hypothalamus → ↓ GnRH Blood concentration 4. High estrogen stim LH 15 days Luteal Phase 28 Changes in the uterus: 1. (early phase) Estrogen → development of uterine smooth muscle (myometrium) → Growth of endometrium → Synthesis of progesterone receptors by the endometrium 2. After ovulation, Progesterone → Proliferation of endometrium (glandular & blood vessels) → Inhibit contraction of myometrium 6 Changes in the uterus: 1. If no pregnancy 2. If egg is fertilized: • Corpus luteum degenerates (14 days) ↓ estrogen & progesterone → Constriction of blood vessels and disintegration of endometrial tissue → Release of myometrial inhibition, smooth muscle contractions Later in pregnancy Early in pregnancy trophoblast Placenta Human chorionic gonadotropin ≡ LH Progesterone & estrogen Corpus luteum birth Human chorionic gonadotropin Level in mother’s blood progesterone estrogen 0 1 3 9 months 7
